[RFI] RFI Noise - Part II

K8TB k8tb at bosscher.org
Sat Jul 6 16:45:53 EDT 2013

I have to drop in my story, which was solved 2 weeks ago.

On our local repeater, a fellow ham who works at the large local 
hospital, was concerned as one of the doctors there was being charged 
with interference to a CB'er. I contacted the doctor, and cool part was 
that he very much knew the difference between amateur radio and cb'ers. 
I then contacted the CB'er.

He was not easy to deal with. Somewhat belligerent. I also did not trust 
any of his "troubleshooting". He was adamant that the doctors house was 
causing the problem. The noise the CB'er was being bothered with came on 
around 9:15 PM, and lasted for 12 hours. I found this when I visited him 
with a ham buddy. I drew on all my knowledge of Law n Order to ask the 
questions properly.

It was 9 PM, so he then drove his SUV with his CB rig (on Channel 37), 
to the power pole in front of the doctors house. The CB'es antenna/tower 
is about 500 feet away. Right at 9:22PM, his mobile CB rig went from S2 
(he had two preamps in series in his mobile!) to S9. I had my FT-817 
dialed into 27.375 (Channel 37), and my National DF loop. My noise went 
up to an S2. But, I immediately could tell that the signal was not 
coming from this area. Every 100 feet, I could tell I was closer. The 
noise was a very broad band AC buzz. I ended up around 500 feet away 
from the doctors power pole, and then I could not get a null, as I had 
all kinds of secondary power lines overhead. The noise was now S9 ++

I went back to my car, dug out my Arrow 3 element 2 meter beam, and my 
VK3YNG sniffer. From my car, I walked back to my last spot, and as I 
walked, the noise, on 2 meters, very sharpley pointed to one house. The 
home owner was working on a car just outside his garage. I called to him 
from the sidewalk. My ham radio buddy joined. I explained that we were 
looking for electronic noise in the neighborhood. He told me, "Ya, 
something bothering a lot of stuff in my house!". Holding teh 
sniffer/beam to his power meter caused the sniffer to go to 60 Db 
attenuation.  I told him that to the best of our ability, the noise was 
coming from his house. I then told him that the noise was on for 12 
hiours and off for 12 hours. He then told me that he had grow lights on 
a 12 hour time, but they were not due to come on until 10 PM. I asked if 
we could tun off the timer. He said, no wait here. He went downstairs, 
and the noise was gone in 30 seconds. He came back, and could not 
apologize enough. He had checked several of his electronic devices and 
the noise was gone. He never made the connection.

We offered to have a look see at the ballast, and he said, "No!". Now, 
could he be growing pot? Not necessarily. Many people don't want 
strangers in their house. I understand that.

The CB'er? Because he was parked by the doctors power pole when the 
timer kicked in, it had to be the doctor. If he had just backed up 500 
feet, he would have learned more. Reminds me of so many mistakes 
beginning DF'ers make. The CB'er also told us "He wanted words with this 
neighbor". We told him no.

My ham buddy knew the neighbor with the bad ballast from a work 
situation, and politely asked to come back in one week to verify the 
noise was gone. The neighbor was very wiling for that. That neighbor was 
insistent that the bad ballast would be gone. I felt he was embarrassed.

The doctor was very very happy. No, he did not offer a free exam for our 

But years of monitoring this forum helped me in troubleshooting this. 
Thank you to all for the hints from the past.

Tom Bosscher K8TB

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